The process for preparing catalysts active for the acetoxylation of ethylene to produce vinyl acetate are known for example from European patent publication EP-A-0672453 which relates to a process for the preparation of a fluid bed catalyst comprising impregnating a support comprising a mixture of substantially inert microspheroidal particles with a solution comprising salts of palladium and a metal M selected from the group consisting of barium, gold, lanthanum, niobium, cerium, zirconium, lead, calcium, strontium, antimony and mixtures thereof. EP-A-0672453 describes preparation processes in which metal salt compounds are reduced using hydrazine.
Several processes are described for the treatment of hydrazine containing aqueous streams. These involve decomposition of hydrazine with an oxidising agent in the presence of a noble metal or base metal catalyst (e.g. JP 2000107774, JP 63205194, JP 63036894). This oxidative decomposition may also be performed in the presence of alkali (e.g. JP 63049295). In the absence of an oxidant hydrazine is readily decomposed either thermally or in the presence of a catalyst to nitrogen and/or ammonia.